#include"bits/stdc++.h"

//#include<bits/stdc++.h>
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 100000000000;

int n, x[100002], y[100002];
bool now[100002];

int main() {
	cin >> n;
	bool flag = 1;
	REP(i, n)cin >> x[i] >> y[i];
	REP(i, n) {
		flag = 1;
		rep(j, 0, i) {
			if (now[j] == 0)continue;
			ll dist = pow(x[i] - x[j], 2) + pow(y[j] - y[i], 2);
			if (dist < 400) {
				flag = 0;
			}
		}
		if (flag)now[i] = 1;
	}
	int count = 0;
	REP(i, n)if (now[i])count++;
	print(count);
	return 0;
}